Response to nebulizaed ipratropium bromide and terbutaline in acute severe asthma

Outpatient studies on asthmatics have shown that inhaled anti-cholinergic agents decrease in efficacy as FEV 1 falls. To determine whether there are changes in response to inhaled anti- cholinergics during acute broncho-constriction we have examined the effects of nebulized ipratropium and terbutaline in nine hospitalized patients recovering from acute severe asthma. At 6 a.m. each day throughout the admission, baseline PEFR was recorded. Ipratropium bromide, 1 mg, was nebulized and PEFR measured again 1 h later. Following this, terbutaline, 5 mg, was nebulized with further measurement of PEFR 15 min after nebulization. Results were analysed by paired t - tests. Mean baseline PEFR rose from 1571 m −1 on patients worst day to 3001 m −1 on their best day ( P -1 and 421 m −1 on patients worst and best days respectively ( P -1 ( P −1 on their best day ( P =0.09). Hence, ipratropium produced 96% of total bronchodilatation when baseline was highest, but achieved only 71% of total response when baseline was lowest, a highly significant change in response ( P